Of interest is copending application Ser. No. 811,824, filed concurrently herewith, entitled "Printed Circuit Board Assembly and Method for the Manufacture Thereof" by Robert Warren Jebens and Gerard Samuels, and assigned to the assignee of the present invention.
Printed circuit board assemblies (hereinafter referred to as PCB assemblies) are used in the manufacture of electrical apparatus, such as television receivers, video cassette recorders, computers and the like. The PCB assemblies which are most commonly employed in electrical apparatus are comprised of an insulative substrate having printed circuitry formed on one surface of the substrate and leaded electrical components mounted on the opposite surface of the substrate, with the leads of the electrical components extending through apertures in the substrate and being electrically connected to the printed circuitry. More recently, PCB assemblies have come into commercial use which have printed circuitry on both surfaces and also include surface mounted components wherein the components are soldered directly to the printed circuitry.
All but the most simple types of electrical apparatus generally require a number of different types of PCB assemblies. Certain of the PCB assemblies are preferably positioned at certain locations in the electrical apparatus. For example, in consumer products such as televisions, video cassette recorders, home computers and the like, the operating controls are typically located at the face surface of the electrical apparatus and, accordingly, the PCB assemblies, which include the operating control components, are likewise located adjacent the face surface of the electrical apparatus. On the other hand, the gross adjustments, electrical power connectors, cable connectors and the like, are typically located at the rear of the electrical apparatus and, accordingly, the PCB assemblies, including the rear mounted components, are located adjacent the back surface of the electrical apparatus. Other types of PCB assemblies, such as the kinescope circuit board of a television set receiver, are required to be mounted at a specific funtionally defined location within the electrical apparatus, as, for example, on the end of the television picture tube. There are also often space limitations within the electrical apparatus which prevent mounting all the required electrical components on a single PCB assembly. In latter situations, it is common practice to use a number of separate smaller PCB assemblies which are mounted at various locations within the electrical apparatus.
It is conventional practice when the electrical apparatus contains a number of different types of PCB assemblies to manufacture all of the required number of a particular type of PCB assembly in a batchwise fashion. The different types of PCB assemblies required for the electrical apparatus may be manufactured at different locations, at different times and under substantially different production conditions.
When the required number of each type of PCB assemblies has been manufactured, the PCB assemblies are sent to an assembly area. In the typical assembly process, each of the various types of PCB assemblies is initially physically secured with brackets, screws or the like, in prescribed locations relative to the chassis of the electrical apparatus being assembled. Thereafter, the individual PCB assemblies are electrically connected to each other using connector cable, jumper wires or the like. The electrical connection of the individual PCB assemblies is typically performed in a soldering operation on the final assembly line.
The conventional method of manufacturing electrical apparatus which include a plurality of PCB assemblies, such as that generally described above, has many inherent problems. The batchwise manufacture of each of the individual types of printed circuit boards required for a particular electrical apparatus inherently increases the overall manufacturing cost and can result in a substantial increase in the rejection rate for the final assembled electrical apparatus. Since all of the different types of PCB assemblies must be prepared prior to the final assembly of the electrical apparatus, a substantial number of each type of PCB assembly must be inventoried which adds to the overall production cost. Furthermore, a shortage of one of the required types of PCB assemblies can cause an expensive shutdown of an entire final assembly line.
A still further and even more serious problem is that even if an adequate supply of PCB assemblies is maintained, if all PCB assemblies made in a particular batch are found defective, as, for example, because of poor wave soldering, the entire final product made with the defective PCB assemblies will also be defective. A still further problem with the batch method of making each type of PCB assemblies is that the individual PCB assemblies, when separately inspected prior to final assembly, may appear to be satisfactory, but when electrically connected with other types of PCB assemblies manufactured under slightly different conditions, may prove to be electrically incompatable due to differences in the printed circuit boards, metal composition of the solders, the soldering condition employed in the manufacture of the PCB assemblies and other similar problems.
Another serious problem is that the mechanical attachment and the electrical connection of the individual PCB assemblies during final assembly of the electrical apparatus is expensive and time-consuming. Furthermore, the electrical leads connecting the individual PCB assemblies must be precisely positioned and correctly soldered in order for the assembled electrical apparatus to operate properly. However, under the conditions generally encountered during final assembly, considerable errors are often made which require expensive troubleshooting and rework to correct the errors. Even if the electrical leads are properly connected, the large number of exposed wires and connections are a constant source of problem in that during assembly, and during maintainence, the connections easily can be broken inadvertently.
It would be highly desirable if a method could be provided for producing more reliable PCB assemblies which more simply and with less defects could be mechanically secured and electrically connected to other components of an electrical apparatus during final assembly of the electrical apparatus.